Interim Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Total SVBFG Stockholders’ Equity	Noncontrolling Interests
Balance (in shares) at Dec. 31, 2017		52,835,188
Balance, beginning of period, net of tax at Dec. 31, 2017	$ 4,319,415	$ 53	$ 1,314,377	$ 2,866,837	$ (1,472)	$ 4,179,795	$ 139,620
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Reclassification of stranded tax effect for ASU 2018-02	319
Reclassification of stranded tax effect for ASU 2018-02 | Accounting Standards Update 2018-02				319	(319)
Common stock issued under employee benefit plans, net of restricted stock cancellations (in shares)		405,395
Common stock issued under employee benefit plans, net of restricted stock cancellations	9,108	$ 0	9,108			9,108
Common stock issued under ESOP (in shares)		9,672
Common stock issued under ESOP	2,577		2,577			2,577
Net income	736,417			707,576		707,576	28,841
Capital calls and distributions, net	(22,785)						(22,785)
Net change in unrealized gains and losses on AFS securities, net of tax	(70,763)				(70,763)	(70,763)
Amortization of unrealized holding gains on securities transferred from AFS to HTM, net of tax	(2,830)				(2,830)	(2,830)
Foreign currency translation adjustments, net of tax	(3,855)				(3,855)	(3,855)
Share-based compensation, net	33,968		33,968			33,968
Balance (in shares) at Sep. 30, 2018		53,250,255
Balance, end of period, net of tax at Sep. 30, 2018	5,070,045	$ 53	1,360,030	3,672,696	(108,410)	4,924,369	145,676
Balance (in shares) at Jun. 30, 2018		53,210,627
Balance, beginning of period, net of tax at Jun. 30, 2018	4,804,841	$ 53	1,346,586	3,397,879	(86,865)	4,657,653	147,188
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Reclassification of stranded tax effect for ASU 2018-02	0
Common stock issued under employee benefit plans, net of restricted stock cancellations (in shares)		39,628
Common stock issued under employee benefit plans, net of restricted stock cancellations	1,943		1,943			1,943
Net income	281,365			274,817		274,817	6,548
Capital calls and distributions, net	(8,060)						(8,060)
Net change in unrealized gains and losses on AFS securities, net of tax	(17,908)				(17,908)	(17,908)
Amortization of unrealized holding gains on securities transferred from AFS to HTM, net of tax	(1,283)				(1,283)	(1,283)
Foreign currency translation adjustments, net of tax	(2,354)				(2,354)	(2,354)
Share-based compensation, net	11,501		11,501			11,501
Balance (in shares) at Sep. 30, 2018		53,250,255
Balance, end of period, net of tax at Sep. 30, 2018	5,070,045	$ 53	1,360,030	3,672,696	(108,410)	4,924,369	145,676
Balance (in shares) at Dec. 31, 2018		52,586,498
Balance, beginning of period, net of tax at Dec. 31, 2018	5,264,843	$ 53	1,378,438	3,791,838	(54,120)	5,116,209	148,634
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Reclassification of stranded tax effect for ASU 2018-02	0
Acquisition of SVB Leerink	5,256						5,256
Common stock issued under employee benefit plans, net of restricted stock cancellations (in shares)		487,101
Common stock issued under employee benefit plans, net of restricted stock cancellations	9,236	$ 0	9,236			9,236
Common stock issued under ESOP (in shares)		14,442
Common stock issued under ESOP	3,506		3,506			3,506
Net income	909,901			874,000		874,000	35,901
Capital calls and distributions, net	(32,002)						(32,002)
Net change in unrealized gains and losses on AFS securities, net of tax	173,235				173,235	173,235
Amortization of unrealized holding gains on securities transferred from AFS to HTM, net of tax	(1,275)				(1,275)	(1,275)
Foreign currency translation adjustments, net of tax	(4,550)				(4,550)	(4,550)
Net change in unrealized gains and losses on cash flow hedges, net of tax	22,863				22,863	22,863
Share-based compensation, net	50,550		50,550			50,550
Common stock repurchases (in shares)		(1,532,210)
Common stock repurchases	(352,511)	$ (1)		(352,510)		(352,511)
Balance (in shares) at Sep. 30, 2019		51,555,831
Balance, end of period, net of tax at Sep. 30, 2019	6,048,469	$ 52	1,441,730	4,312,745	136,153	5,890,680	157,789
Balance (in shares) at Jun. 30, 2019		51,561,719
Balance, beginning of period, net of tax at Jun. 30, 2019	5,706,175	$ 52	1,421,565	4,051,194	81,232	5,554,043	152,132
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Reclassification of stranded tax effect for ASU 2018-02	0
Common stock issued under employee benefit plans, net of restricted stock cancellations (in shares)		19,674
Common stock issued under employee benefit plans, net of restricted stock cancellations	1,383		1,383			1,383
Net income	281,718			267,281		267,281	14,437
Capital calls and distributions, net	(8,780)						(8,780)
Net change in unrealized gains and losses on AFS securities, net of tax	50,638				50,638	50,638
Amortization of unrealized holding gains on securities transferred from AFS to HTM, net of tax	(270)				(270)	(270)
Foreign currency translation adjustments, net of tax	(4,482)				(4,482)	(4,482)
Net change in unrealized gains and losses on cash flow hedges, net of tax	9,035				9,035	9,035
Share-based compensation, net	18,782		18,782			18,782
Common stock repurchases (in shares)		(25,562)
Common stock repurchases	(5,730)	$ 0		(5,730)		(5,730)
Balance (in shares) at Sep. 30, 2019		51,555,831
Balance, end of period, net of tax at Sep. 30, 2019	$ 6,048,469	$ 52	$ 1,441,730	$ 4,312,745	$ 136,153	$ 5,890,680	$ 157,789